The present invention relates to the art of earth boring and, more particularly, to a rotary rock bit with improved means for sealing the bearings of the bit from materials in the borehole and retaining lubricant within the bearing area. The present invention is especially adapted for use with rock bits popularly known as three cone rotary rock bits; however, its use is not restricted thereto, and the present invention can be used in other types of rotary rock bits.
A three cone rotary rock bit consists of a main bit body adapted to be connected to a rotary drill string. The bit includes three individual rotatable cone cutters mounted on three individual bearing pins extending from the main bit body. Bearing systems are provided between the cone cutters and the bearing pins to promote rotation of the cutters and means are provided on the outer surface of the cone cutters for disintegrating the earth formations as the bit and the cutters rotate. A sufficient supply of uncontaminated lubricant must be maintained proximate the bearing systems throughout the lifetime of the bit. Various forms of seals have been provided between the cone cutters and the bearing pins upon which they are mounted to retain lubricant and prevent contamination; however, the need for new sealing systems is as acute today as any time in the history of rock drilling.
A three cone rotary rock bit must operate under very severe conditions and the size and geometry of the bit is restricted by the operating characteristics. At the same time, the economics of petroleum production demand a longer lifetime and improved performance from the bit. In attempting to provide an improved bit, new and improved materials have been developed for the cutting structure of the cone cutters. This has resulted in the bearing systems of the bit being often the first to fail during the drilling operation. Consequently, a need exists for new and improved bearing systems to extend the useful lifetime of the bit and to allow development of other elements that interact with the sealing and bearing systems. In attempting to improve the bearing systems, various seal systems have been provided to maintain the bearing area free of harmful materials and retain lubricant. In attempting to provide new sealing systems, great care must be taken that the overall capacity of the bearing systems is not reduced.